1988 Volume 74 Issue 7 Pages 1454-1461
A study was made on effects of hot charge rolling(HCR) on the mechanical properties and microstructures of the plate, in relation to the behaviors of austenite (γ) grains and precipitates.
In this process, it becomes very difficult to refine γ grains by conventional controlled-rolling, because of the coarse as-cast γ grains before rolling.
Therefore, low-temperature toughness remarkably deteriorates. In order to improve low-temperature toughness of HCR plate, the optimum rolling method of γ grains was examined in the recrystallization and non-recrystallization regions of γ.
On the other hand, it is possible to get higher strength in HCR process, compared with that in conventional process, because precipitation-hardening elements such as Nb are fully dissolved. The strength of HCR plate, however, strongly depends on the processing conditions.
Furthermore, it was found that a microalloyed Ti of about 0.01 % remarkably raises the strength by the precipitation-hardening in HCR process.